The so-called degaussing, in fact, the magnetic does not disappear, just change the magnetic field distribution of the magnet through the magnetically permeable material.
The degaussing package is generally isolated by iron sheets. The six faces inside the box are fixed, and then the pearl cotton bag is used, and then the carton is used for packing. For some magnetic weak magnets, the airline can be checked. Some magnetically dissipative materials sold on the market can also play a better degaussing effect, reassembling the powerful magnets, and reducing the magnetic properties of the powerful magnets, so that the powerful magnets can be taken to the aircraft through the security inspection of the airline.
The principle of magnetic isolation is to shield the magnetic field. It refers to the steady magnetic field or the low frequency magnetic field. It mainly depends on the magnetic field circuit. If the box is made of high magnetic permeability material, the magnetic field line that would otherwise be worn out of the box is concentrated on the box material. Closed, so that the magnetic lines of force leaking out of the box are greatly reduced. In order to achieve magnetic field shielding, the higher the magnetic permeability of the material, the better; the same material, the thicker the better; the same material and thickness, the more layers, the better. In addition, the magnet should be placed in the center of the shielding box to avoid more concentrated magnetic lines on one side and more leakage.
If you want to shield the high-frequency magnetic field, you can use a method: using a well-conducting material such as metal, using a high-frequency magnetic field to form an alternating eddy current on it, forming an opposite magnetic field to cancel the original magnetic field, essentially two The magnetic field is superimposed, and the outer phase of the shield is cancelled, and a new magnetic circuit is synthesized inside the shield. Regarding the second point, the material is magnetized. The magnetically permeable material is always magnetized in the magnetic field, but in addition to the hard magnetic material, once the external magnetic field is removed, the magnetic is quickly followed. Therefore, if the shielding material is made of hard magnetic material and a new independent magnetic field is formed, the effect will be affected. This is because the shielding can only use soft magnetic materials. (If you ask, the soft magnetic material will be magnetized in the magnetic field, how to complete the shielding? This is because the soft magnetic material is magnetized, and the resulting new magnetic field strength, completely independent of the external field strength. Change, and then according to the high-frequency magnetic field shielding principle mentioned above, destructively achieve "shield". "Magnetic line" is the image, the essence is the superposition of the field.) Magnetic shielding in vacuum, because the air is a paramagnetic substance, The magnetic permeability is slightly larger than the vacuum, so theoretically the magnetic shielding effect in vacuum is better than in the air, but the effect on engineering is minimal. Because the ratio of the magnetic permeability of the relative vacuum of the paramagnetic substance and the diamagnetic substance (that is, the relative magnetic permeability) is almost 1, which is not more than a few thousandths; and the relative conduction of the magnetic conductive material (ferromagnetic substance) The magnetic rate is hundreds of thousands, even over 10,000 and over 100,000. In comparison, the existence of paramagnetic and diamagnetic materials in engineering is often not considered.
